[Tired Old Man]

There's a whole bunch of different influences on the airframe in knife edge. The CG and horizontal stab location are two of the biggies, but also involved are engine thrust line, shape of the fuselage, location and shape of the canopy, propeller type and pitch, rudder size, location of the main wing relative to the horizontal stab, wing and stab relative incidence,and a few other things.

Just go for the mix that works the best after the cg and engine thrust are established. You can also reflex the ailerons up a little.

The George Hicks article was very good reading if you can find it.

Reason for a Yak 55 or a Sukhoi?

They both have the least amount of natural pitch coupling in knife. The 55 is a little better in a few other things as well because the rudder extends a bit below the fuselage.